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Abstract:

A backlight module is provided. The backlight module includes a light
guide plate, an optical component, and a light source for generating
light. The optical component is provided for adjusting or veering the
light emitted from the light source along a direction perpendicular to
the light guide plate. One end of the optical component is affixed to the
light source for receiving the incident light. The other end of the
optical component faces, and is separated from, the light guide plate, so
as to direct the light to the light guide plate.

Claims:

1. A backlight module, comprising:a light source for generating light;a
light guide plate; andan optical component configured to adjust the light
along a direction perpendicular to said light guide plate;wherein one end
of said optical component is affixed to said light source for receiving
the incident light, and the other end of said optical component faces,
and is separated from said light guide plate, so as to direct the light
to said light guide plate.

2. A backlight module according to claim 1, wherein said optical component
is provided for focusing the incident light.

3. A backlight module according to claim 1, wherein said optical component
is a cylindrical lens.

4. A backlight module according to claim 3, wherein said cylindrical lens
has a convex surface facing said light guide plate and has a plain
surface facing said light source.

5. A backlight module according to claim 3, wherein said cylindrical lens
has a radius of curvature not smaller than a distance between said
cylindrical lens and said light guide plate, so as to focus the light
into said light guide plate.

6. A backlight module according to claim 3, wherein said cylindrical lens
is integratedly formed with said light source and is provided for
encapsulating said light source.

7. A backlight module according to claim 1, wherein said light guide plate
has a plain side for receiving said incident light.

8. A backlight module according to claim 1, wherein said light source is a
side-view LED.

9. A backlight module according to claim 1, wherein said light source and
said optical component are affixed to each other by optical glue.

10. A backlight module according to claim 1, wherein said optical
component is integratedly formed with said light source and is provided
for encapsulating said light source.

11. A display apparatus, comprising:a backlight module, comprising:a light
source for generating light;a light guide plate; andan optical component
configured to adjust the light along a direction perpendicular to said
light guide plate;wherein one end of said optical component is affixed to
said light source for receiving the incident light, and the other end of
said optical component faces, and is separated from said light guide
plate, so as to direct the incident light to said light guide plate.

12. A display apparatus according to claim 11, wherein said optical
component is a cylindrical lens.

13. A display apparatus according to claim 12, wherein said cylindrical
lens has a convex surface facing said light guide plate and has a plain
surface facing said light source.

14. A display apparatus according to claim 12, wherein said cylindrical
lens has a radius of curvature not smaller than a distance between said
cylindrical lens and said light guide plate, so as to focus the light
into said light guide plate.

15. A display apparatus according to claim 12, wherein said cylindrical
lens is integratedly formed with said light source and is provided for
encapsulating said light source.

16. A display apparatus according to claim 11, wherein said light guide
plate has a plain side for receiving said incident light.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]This application claims the right of priority based on Taiwan Patent
Application No. 097104079 entitled "BACKLIGHT MODULE AND DISPLAY
APPARATUS HAVING THE SAME", filed on Feb. 1, 2008, which is incorporated
herein by reference and assigned to the assignee herein.

FIELD OF INVENTION

[0002]The present invention relates to a backlight module and a display
apparatus having the same; particularly, the present invention relates to
a backlight module adopting LED light source and a display apparatus
having the same.

BACKGROUND OF THE INVENTION

[0003]A liquid crystal display (LCD) device has various advantages, for
example, a high resolution, low driving voltage, low power consumption,
thin thickness, small volume and light weight as compared with a cathode
ray tube (CRT) device, making it ideal for use in a variety of
applications, such as portable computers, communication devices, mobile
devices, television sets, etc.

[0004]Generally, the LCD device includes two main parts: a liquid crystal
panel and a backlight module. The backlight module is employed for
providing planar light source of a uniform luminance into the LCD panel.
When such a light is incident into the panel from the backlight module, a
uniform image is displayed through an entire effective display area of
the panel.

[0005]The backlight assembly may include a light guide plate and a light
source for generating light. For example, the light source may be a cold
cathode fluorescent lamp (CCFL) or a light emitting diode (LED). The LED
is usually employed for a display device having a relatively small
display unit, such as a mobile communication device, to thereby reduce
the volume and the power consumption thereof. It is observed that
large-size LCD TVs on the market are starting to adopt LEDs as backlight.

[0006]FIG. 1 is a side view of a conventional LED backlight module 100,
which includes a LED light source 102 and a light guide plate 104. A
light generated from the LED typically corresponds to a point light and
has a large divergent angle θ, around 110 to 120 degrees (measured
based on FWHM of the luminosity). However, the thickness of the light
guide plate 104 is around 0.4 to 2.0 mm, which is quite thin relative to
the large divergent angle of the LED light source 104, so that only a
limited portion of light is coupled into the light guide plate 104,
resulting in low coupling efficiency.

[0007]The conventional solutions increase the brightness or the numbers of
LED to increase the total output from backlight module. However,
inevitably they would add up the manufacture cost and make the circuit
design more complicated. Therefore, it is desired to have a new,
inexpensive, and simple-implemented backlight module to solve
aforementioned problems.

SUMMARY OF THE INVENTION

[0008]Various embodiments related to providing a backlight module and a
display apparatus having the same. The backlight module has a light
source, a light guide plate, and an optical component. In one aspect, the
light is adjusted or veered along a direction perpendicular to the plane
of light guide plate, so as to allow more light emitted from the light
source to enter the light guide plate and thus raise the coupling
efficiency. In another aspect, an optical component is disposed between
the light source and the light guide plate to adjust or veer the light
emitted from the light source.

[0009]In one embodiment, what disclosed is a backlight module including a
light guide plate, an optical component, and a light source for
generating light. The optical component is provided for adjusting or
veering the light emitted from the light source along a direction
perpendicular to the light guide plate. One end of the optical component
is affixed to the light source for receiving the incident light. The
other end of the optical component faces, and is separated from, the
light guide plate, so as to direct the incident light to the light guide
plate. Particularly, the optical component can be implemented as a
cylindrical lens for focusing the incident light in the direction
perpendicular to the plane of light guide plate.

[0010]In another embodiment, disclosed is a display apparatus having a
backlight module. The backlight module includes a light guide plate, an
optical component, and a light source for generating light. The optical
component is provided for adjusting or veering the light along a
direction perpendicular to the plane of light guide plate. One end of the
optical component is affixed to the light source for receiving the
incident light. The other end of the optical component faces, and is
separated from, the light guide plate, so as to direct the light to the
light guide plate. Particularly, the optical component can be implemented
as a cylindrical lens.

[0011]The foregoing and other features of the invention will be apparent
from the following more particular description of embodiment of the
invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]The above and other features and advantages of the present invention
will become more apparent by describing in detailed exemplary embodiments
thereof with reference to the accompanying drawings, in which:

[0013]FIG. 1 illustrates a conventional backlight module;

[0014]FIG. 2A is a side view of the display apparatus according to an
embodiment of the present invention;

[0015]FIG. 2B is a top view of the display apparatus according to an
embodiment of the present invention; and

[0016]FIG. 2c is a perspective view of the display apparatus according to
an embodiment of the present invention.

DETAILED DESCRIPTION

[0017]As known to those skilled in the art, the display apparatus 20
illustrated in FIGS. 2A and 2B is preferably a liquid crystal display
apparatus and can be incorporated into a mobile phone, a personal digital
assistant (PDA), a notebook computer, a desktop computer, a television, a
car media player, a portable video player, a digital camera, a global
positioning system (GPS), an avionics display, etc. Note that the present
invention is illustrated by way of example and not intended to be limited
by the figures of the accompanying drawing. The scales, the sizes, and
the relative positions of the illustrative elements in the drawing should
not limit the scope of the present invention.

[0018]As shown in FIG. 2A, in order to display an image, the display
apparatus 20 has a backlight module 200 to provide a planar light of a
uniform luminance B into the panel (not shown) of the display apparatus
20. A perspective view of the display apparatus 20 can be seen in FIG.
2C.

[0019]The backlight module 200 includes a light guide plate 204, an
optical component 206, and a light source 202 for generating light, which
is to be coupled into the light guide plate 204 via the optical component
206. The light source 202 could be a light emission diode (LED) of red-,
green-, or blue-light. Preferably, the light source 202 is a white-light
LED. Note that the number or the size of the light source 202 should not
limit the present invention. According to the size and the intended
purpose of the display apparatus 20, those skilled in the art should be
able to select appropriate LED light sources for the backlight module. In
the following description for the exemplary purpose, the light source 202
is a single white light LED. Preferably, LED 202 is a side-view LED, with
thickness of 0.2 mm to 2.0 mm. Disposed on a circuit board (e.g., a
flexible print circuit board, not shown), LED 202 is further connected to
a control circuit (not shown either). To minimize the thickness of the
product and to save the assembling cost, side-view LEDs are generally
adopted in the display for the mobile device. Meanwhile side-view LEDs
should be known to those skilled in the art and the details of the
side-view LED are omitted thereinafter.

[0020]As shown in FIG. 2B, the light guide plate 204 has a plain side 205
to receive the light A, which is emitted from the light source 202 and
passed by the optical component 206. Further referring to FIG. 2c, the
reflective plate and light guide structure in the light guide plate 204
transform the light A into planar light of a uniform luminance for the
panel (not shown) of the display apparatus 20. In other embodiments, the
side 205 is not plain, but is formed as other geometrical structures to
make the light incident to the light guide plate 204 even uniform.

[0021]Now refer back to FIG. 2A. In the embodiment, the light guide plate
204 is a plain plate with thickness of 0.4 mm, 0.6 mm, or 0.8 mm.
Generally, the thickness t2 of the light guide plate 204 is substantially
equal to the height t1 of LED 202 (but may be larger or less than height
t1). In other embodiments, the light guide plate 204 has a wedge
structure, which has the thickest end on the side 205 and gets thinner
away from the side 205.

[0022]One end of the optical component 206 is affixed to the light source
202 for receiving the light. The other end of the optical component 206
faces, and is separated from the side 205 for a distance D, so as to
direct the light to the light guide plate 204. The optical component 206
is provided for adjusting or veering the light from the light source 202
in the direction perpendicular to the plane of light guide plate 204.

[0023]Referring to FIGS. 2B and 2C, the light guide plate 204 is disposed
on the x-z plane, and the optical component 206 (shown in FIG. 2A)
directs the light in y-direction. In one embodiment, the optical
component 206 adjusts the divergent angle θ in the y-direction. In
the embodiment shown in FIG. 2A, the optical component 206 is a
cylindrical lens for focusing the incident light, i.e., narrowing the
divergent angle θ in y-direction, and for adjusting the incident
angle corresponding to the position of the side 205, so as to
successfully couple a larger amount of light into the light guide plate
204, compared with the prior art. Note that in various embodiments, the
optical component is not limited to lens, and could be implemented as
refractive elements, diffractive elements (like optical gratings), or the
combination thereof.

[0024]Various embodiments will be made clearer by the following example
with the cylindrical lens 206, which has a convex surface facing said
light guide plate 204 and has a plain surface facing said light source
202. In FIG. 2A, one end (the plain surface) of the cylindrical lens 206
is affixed, by general optical glue, to the LED 202 for receiving the
light. In another embodiment, the cylindrical lens 206 is integratedly
formed with the LED 202 by molding for encapsulating the LED 202.

[0025]The other end (the convex surface) of the cylindrical lens 206 faces
the light guide plate 204. Meanwhile it is separated from the light guide
plate 204 for a distance D (around 0.3 mm, depending on the mechanical
design), so as to direct the light from the light source 202 to the light
guide plate 204. Once the distance D is given, the coupling efficiency of
the light guide plate 204 is further determined by the radius of the
curvature R of the convex surface of the cylindrical lens 206. In a
preferred embodiment, the radius of the curvature R is not smaller than
the distance D. Meanwhile, the thickness t2 of the light guide plate 204
affects the coupling efficiency. Generally speaking, a larger thickness
results in a better coupling efficiency. In alternative embodiments, when
D is 0.3 mm and the thickness t1 is around 0.6 to 0.8 mm, the radius of
the curvature R can be selected from 0.3 mm, 0.4 mm. 0.5 mm, 0.6 mm, and
1 mm, and the thickness t2 can be selected from 0.8 mm, 1.2 mm, 1.6 mm,
2.0 mm, and 2.4 mm.

[0026]With the embodiments described above, various embodiments provide a
backlight module and a display apparatus having the same. The coupling
efficiency of the light guide plate is increased by adjusting or veering
the incident light emitted from the light source along a direction
perpendicular to the light guide plate. Compared to the conventional
design, various embodiments are easy to implement without adding much
cost.

[0027]While various examples been described with reference to the
illustrative embodiments, these descriptions should not be construed in a
limiting sense. Various modifications of the illustrative embodiment, as
well as other embodiments of the invention, will be apparent upon
reference to these descriptions. It is therefore contemplated that the
appended claims will cover any such modifications or embodiments as
falling within the true scope of the invention and its legal equivalents.